The semi-transparent solar concentrator of the research team can be covered directly with standard window glass. It uses liquid crystal films to reflect circularly polarized sunlight and lead to solar cells installed to the edge of a window. A prototype of 1 inch diameter was found able to immediately feed a 10 MW fan under sunlight.
A research team established on Chinese Nanjing University has developed a transparent, colorless and unidirectional solar center plant that is compatible with existing windows.
Solar concentrators are designed to converge solar energy to the side of architectural glass. Handy with building-integrated photovoltaic, existing solar concentrators often suffer from setbacks, including low efficiency, colors or a lack of compatibility with existing windows.
The newly developed DRIFFRACFIVE DIFFRACFIE Type solar concentrator (CUSC) of the research team uses cholesteric liquid crystal (CLC) Multi-layered layers with submicron lateral periodicity to selectly lead the edge of the window where photo-movoltaic cells are installed. The team manufactured the multi-layered CLC films via photo lines and polymerization techniques, which are scalable via roll-to-roll production.
Under tests, the CUSC device retained an average visible transmission of 64.2% and the color reproduction index of 91.3, which made energy generation possible without changing the appearance of the window.
“By engineering the structure of cholesteric liquid films, we create a system that selectively deviates circularly polarized light and leads it in the glass wave conductor under steep corners,” said DeWei Zhang, co-first author of the research. “This allows a maximum of 38.1% of the incident green light energy to be collected on the edge.”
The research paper “Colorless and Unidirectional Difractive Type Solar Central Centers Compatible with existing windows“Available in the magazine PhotonixDetails how a prototype of a diameter of 1 inch diameter was found capable of feeding a 10 MW fan directly under sunlight.
Further modeling showed that a typical 2-meter wide CUSC window could concentrate the sunlight 50 times, which reduces the number of photovoltaic cells that are necessary by a maximum of 75%. The design also remained stable with long -term exposure and was found to be suitable for adjustment to existing windows, making sustainable urban upgrades possible.
Professor Wei HU noted that the CUSC design is a step forward in integrating solar technology in the built environment without sacrificing aesthetics. “It represents a practical and scalable strategy for carbon reduction and energy-self-supply,” hu added.
In the conclusion of the research paper, the authors write that the CUSC design would be taken over on a large scale in green buildings, agricultural photovoltaic and other emerging areas. “It is expected to contribute to a global green energy supply on Terawatt scale and reduce the annual carbon emissions with billions of tonnes,” concludes the paper.
The research team says that it is planning to concentrate future work on improving broadband efficiency, polarization control and adjusting technology for agricultural greenhouses and transparent sun displays.
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